Waveguide



A. MULLER.

WAVEGUIDE A ril 18, 1967' 2 Sheets-Sheet 1 Filed March 11, 1965 FIGJ.

uvvgrvrore Alexander Muller BYmZ/V 3 ATTORNEYS A. MULLER WAVEGUIDE April18, 1967 Filed March 11, 1965 2 Sheets-Sheet 2 mdI w x Q J INVENTORAlexander Mijller BYW/E/ @4 ATTORNEYS United States Patent 3,315,185WAVEGUIDE Alexander Miiller, Backnang, Germany, assignor to TelefunkenPatentverwertungsgesellschaft m.b.H., Ulrn (Danube), Germany Filed Mar.11', 1965, Ser. No. 438,978 Claims priority, application Germany, Mar.11, 1964, T 25,791 4 Claims. (Cl. 333-95) The present invention relatesgenerally to the microwave art, and, more particularly, to a device forthe twisting or rotation of the polarization direction of the waves in awaveguide.

It is already known that in waveguides with a rectangular cross sectionthe rotation of the polarization direction of the waves is obtained bytwisting or turning the waveguide in spiral fashion about itslongitudinal axis.

It is furthermore known that the same result can be obtained by certaincombinations of bends or elbows.

But in that case the input and output of the arrangement are displacedparallel to each other and ment is considerably higher.

Recently, a corrugated'waveguide with an oval or elliptical crosssection has been invented as a structural element, which can bepositioned easily due to its high flexibility. Because of its flexiblequality it does not require the use of elbows or similar expensive andheavy ele ments.

If turning of the polarization of the waves in a waveguide is required,then first there must be a change from the flexible corrugated waveguideto a rectangular cross section via a transition or connecting piece.Only then can the turning or twisting of the polarization direction heperformed in the conventional way by a rectangular waveguide twistedabout its longitudinal axis. This entails a considerable expenditure.One solution is to twist the corrugated waveguide about its longitudinalaxis and fix it in the desired position. However, a significant numberof tests have shown that the later twisting of the waveguide about itslongitudinal axis requires such a large force, that it can not, with atolerable expenditure, be fixed in this position. Besides this, there isusually a separate short twist incorporated into the waveguide which,for example, is 90. If the above-mentioned waveguide was deformed later(at the site where it is to be used) this would lead to its destructionor the cross section would be deformed so irregularly that fault-freetransmission of electromagnetic waves becomes impossible. Furthermore,the machines necessary to perform this operation are not available atthe location where the waveguide is to be used. By the invention howeverit becomes possible to have a waveguide arrangement with twistedsections undivided by flanges and without the necessity of adapters fromoval or elliptical to rectangular cross sections.

With this in mind, it is a main object of the present invention toprovide a corrugated waveguide having an oval or elliptical crosssection which is twisted spirally about its longitudinal axis by acertain angle per unit length.

Another object of the invention is to provide a device of the characterdescribed by means of which turning of the polarization direction can beperformed and the waveguide for accomplishing this can be simply andquickly mounted.

A further object is to provide a waveguide arrangement includingsections for turning the polarization direction and in which thereflection factors are decreased and the permissible productiontolerances are increased in comparison to known devices.

These objects and others ancillary thereto are accomplished inaccordance with preferred embodiments of the invention wherein acorrugated elliptical waveguide is the space require- 3,315,185 PatentedApr. 18, 1967 fabricated having a uniformly angularly varying major axisso that it is twisted spirally about its longitudinal axis by apredetermined angle per unit of length.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a schematic elevational view of a corrugated ellipticalwaveguide made in accordance with the present invention.

FIGURES 2a, 2b and 2c are schematic sectional views taken generallyalong the planes define-d by reference lines a-a, 12-12 and cc,respectively, of FIGURE 1. In the shown example the twist angle isconstant.

FIGS. -3 and 4 show schematically .a waveguide which is twisted in thefirst section in one direction, in the second section untwisted and inthe third section twisted in the opposite direction. The untwistedsection can be of any length. The twist angles of the first and lastsection are independent of each other.

With more particular reference to the drawings, FIG- URE 1 shows acorrugated waveguide provided in accordance with the present invention.The elliptical waveguide 1 is provided with the corrugations 2. On thelefthand side of the device shown, the waveguide can be protectedagainst corrosion and mechanical damage by a wear resistant plastic coat5.

In the plane designated by aa, the: major axis of theelliptically-shaped waveguide is positioned to be what may be consideredvertical, as indicated in the corresponding FIGURE 20. In a further andintermediate plane bb, the major axis is already turned or twisted e.g.by 45 (see FIGURE 2b) compared to the position it has in plane a-a asshown in FIGURE 2a and this is accomplished by twisting the waveguideabout its longitudinal axis. In the plane c-c at the end of thearrangement shown in FIGURE 1, the above-mentioned major axis of thewaveguide cross section is turned e.g. by another 45 compared to thecross section along plane b-b, as can be seen from FIGURE 20. Theassembling part, that is between the two cross sections a-u and ccconsequently represents a so-called waveguide Twister.

The twist angue can be constant for the whole length of the waveguide orcan change in a predetermined manner over the length as described above.

The present invention makes it possible to better utilize the advantagesof the flexible corrugated waveguide especially because the describeddeformation of the structural element is performed when it is producedso that besides saving the additional expensive elements describedabove, a simple and quick mounting is obtained. The use of only oneelement leads furthermore to a decrease of the reflection factors andlarger tolerances in the production of this structural element, whichare equally advantageous.

The required Twist can preferably be placed at the end of a length ofwaveguide which is ordered and this can be done by a suitably developedmachine which produces the hollow conductor. The twist can, however, bedisposed at any desired place within the entire waveguide length whichis manufactured of one piece. The point of use and therefore therequired length of the waveguide are known. It is therefore possible toproduce the complete waveguide length custom made and to obtain anoptimum of transmitting bandwidth with a minimum of reflections, whichis of great importance for radar and radio devices. In the case ofmilitary devices the use of an antenna supply waveguide with a twistfixed, for example, at the end of this waveguide, saves a considerableamount of time, compared to the conventional art, when constructing aradio communications device.

In a mobile device for example the polarisation direction of transmitterand antenna waveguide are known and the mounting of the waveguide isknown at several points, too. For using the possibility of minor bendingradius by bending in parallel to the major axis and for getting thewaveguide on both ends with wanted polarisaton direction such awaveguide arrangement has to incorporate normally one or several twists.Since today it is necessary to use rigid twists which divide thewaveguide arrangement in several flange-coupled sections, winding up thewhole waveguide on a drum is impossible. However twists according to theinvention are flexible, are derived from the untwisted flexiblewaveguide and integral with this Waveguide. There is no source ofunwanted reflexions and the whole arrangement easily can be wound on areel. Also in the case of separate flexible twists according to theinvention inserted with flanges in the waveguide arrangement there isthe possiblity of winding on a reel. These twists may be cut preferablyfrom a continuously twisted waveguide.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes, andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

What is claimed is:

1. A device for the twisting of the polarization direction of the wavesin a waveguide comprising a corrugated elliptical waveguide which, inits unstressed state, has a cross section which is twisted by asubstantial amount about the longitudinal axis of said waveguide by apredetermined angle per unit of length.

2. A waveguide device comprising a length of corrugated hollow conductormaterial which is elliptical in cross section, the cross section of saidconductor when said conductor is in its unstressedstate, being twisted,by a substantial amount about the longitudinal axis of said conductor bya predetermined angle per unit of length.

3. A waveguide device comprising a length of corrugated hollow conductormaterial forming a waveguide and which is elliptical in cross section,the major axis of the ellipse, when said waveguide is in its unstressedstate, turning by a substantial amount about the longitudinal axis ofsaid waveguide by a predetermined angle per unit of length.

4. A device as defined in claim 3 wherein the turning of the major axisof the ellipse is continuous and uniform.

References Cited by the Examiner UNITED STATES PATENTS 2,636,083 4/1953Phillips 333-- 3,008,104- 11/1961 Scapple 33395 3,200,356 10/1965Schuttlofiel 333-95 HERMAN KARL SAALBACH, Primary Examiner.

L. ALLAHUT, Assistant Examiner.

1. A DEVICE FOR THE TWISTING OF THE POLARIZATION DIRECTION OF THE WAVES IN A WAVEGUIDE COMPRISING A CORRUGATED ELLIPTICAL WAVEGUIDE WHICH, IN ITS UNSTRESSED STATE, HAS A CROSS SECTION WHICH IS TWISTED BY A SUBSTANTIAL AMOUNT 